Jellyfish in the sea.
Scuba Divers and snorkelers often ask the question, Are there any Jellyfish out there? The answer is ‘Yes’ we do see them sometimes and occasionally there are hundreds or even thousands of them. The collective name for Jellyfish is ‘A Bloom’.
Jellyfish can be found in all oceans on the planet and have been in existence for more than 500 million years. They can range in size from 1cm up to almost 2 meters in diameter.
Scientific studies have suggested that Jellyfish blooms might be increasing due to factors which may include changes in ocean temperatures and overfishing. With a lack of predators, jellyfish blooms can thrive as they reproduce quickly. Jellyfish feed on miniature sea life such as plankton and as they prey upon smaller fish it might be having an effect on replenishing fish stocks.
Several species will feed on jellyfish including sharks, turtles, and other species of fish.
Are Jellyfish Fish?
Fish are vertebrates (having a Backbone and skeleton) whereas jellyfish are bell-shaped blobs with no bones. Jellyfish do not have a heart or brain but they do have sensors at the end of their tentacles that react to changes in light and temperature. Jellyfish tend to drift along with the ocean currents but they also maneuver by contracting their bell-shaped body to propel themselves through the water.
How to treat a jellyfish sting.
Jellyfish stinging cells are called Nematocysts which are like miniature harpoons that are fired out from their tentacles, but only when you come into contact with them. There are thousands of them in each tentacle.
Remove the tentacles from the infected area and then pour vinegar on the wound, scrape off the remaining stinging cells and finally wash the infected area. The old wives’ tale of using urine does nothing to help.
One of the most deadly creatures on the Planet is the Box Jellyfish which is also known as ‘The Sea Wasp’. The sting from the box jellyfish can be very painful and they have been known to kill humans in just a few minutes.
Observing a large pulsating Jellyfish whilst scuba diving is a fascinating experience, but if you look closely you will notice that there is something more. Many Jellyfish have a shoal of small fish living in around them and occasionally even a tiny crab can be found living inside the bell.
It appears that there are some species of juvenile fish that are immune to the stinging tentacles of the Jellyfish. Juvenile fish are vulnerable growing up in the big ocean, but they can gain some protection whilst they are swimming around between the tentacles of the Jellyfish. This might then be too tempting for any larger fish who could become trapped themselves if they get too close to their prey.
Protection from Jellyfish
When Scuba divers are purchasing their first wet suit and deciding whether to opt for a shorty or a full-length suit, one of the considerations is protection from jellyfish. Even in warm tropical waters, a thin 2mm-3mm suit would give the scuba diver adequate protection from the jellyfish stinging tentacles.
Because Jellyfish react to light, they are usually very close to the surface which means they can be spotted quite easily. If you can see a vast Jellyfish bloom when you arrive at your dive site it would be better to just move the boat to a different location. if there are just a few Jellyfish then grab your camera and let’s go diving!